1. Field of the Invention
The present invention relates to a medical container device having a plurality of bags containing blood and its components, and a method for manufacturing the same.
2. Description of the Related Art
In blood transfusion, for effective use of blood and reduction of an acceptor's load, there has been recently carried out a system in which blood withdrawn from a donor is separated into components by centrifugation or the like and only the components necessary to an acceptor are transfused. By the introduction of the component transfusion, blood has been effectively used as compared with the conventional whole blood transfusion.
In the above component transfusion, a container device (multiple bag) comprises a blood-collecting bag and one or more other bags.
Among the multiple bag, for example, a triple bag consists of the blood-collecting bag, a platelet conserving bag (hereinafter called PC bag) and a plasma conserving bag (hereinafter called plasma bag) which are connected to each other by a tube. Blood collected in the blood-collecting bag is separated into three components, that is, erythrocyte, platelet rich and platelet poor plasma by at least one centrifugal separation (PRP method). Then, these components are contained and conserved in the blood-collecting bag, PC bag, and plasma conserving bag, respectively.
Each bag of such a multiple bag is formed by overlying sheets made of flexible polyvinylchloride and fusing the edge portions. The reason why the sheet material of flexible polyvinylchloride is used is that a sheet made of the material has suitable permeability, suitable preservation of cells such as hemocyte and blood platelet, high heat resistance to autoclaving, and flexibility that bears a centrifuging operation, as well as easy fusion-bonding, easy manufacturing, and low cost of material. Particularly, regarding the blood-collecting bag, there is an advantage in that plasticizer (DEHP and the like) is suitably eluted from the sheet material, and conservation or preservation of erythrocyte in the blood-collecting bag is improved.
However, regarding the PC bag and the plasma bag, the use of a sheet made of flexible polyvinylchloride has the following disadvantages:
Regarding the PC bag, unless the capacity (surface area) of the bag is enlarged or the thickness of the sheet is small, sufficient oxygen and carbon dioxide permeability cannot be obtained, so that the preservation of blood platelet is worsened. Moreover, the plasticizer eluted from the sheet material exerts unfavorable influence on blood platelets. In other words, an activation index (low osmotic pressure shock recovery factor and aggregation) of blood platelet in vitro is lowered.
Moreover, plasma in the plasma bag is normally frozen and preserved. However, the strength of flexible polyvinylchloride is originally low at a low temperature. If there is a shock such as dropping of the plasma bag in a frozen state, fragile breakage is generated in the plasma bag.
In order to solve the above problems, U.S. Pat. No. 4,222,379 discloses a container device wherein the material of the PC bag or plasma bag is different from that of the blood-collecting bag.
However, since the whole body of such a container device is autoclaved, the material of the PC bag and plasma bag must have heat resistance that can resist autoclaving in addition to the above-required properties. Due to this, there is a disadvantage in that the selection of the material is limited. For example, in the case that ethylene-vinyl acetate copolymer (hereinafter called EVA) is used, crosslinking thereof must be performed by radioactive irradiation or a chemical method using peroxide or the like in order to obtain heat resistance that can resist autoclaving (110.degree. C. or more).
Placing emphasis on the above-mentioned heat resistance, various properties necessary to the PC bag, the plasma bag, for example, flexibility, transparency, strength at low temperature, facility of manufacture, economical advantage, or safety, are lost.